Using ADO Programmatically The Connection Object and the Command Object

Using ADO Programmatically To perform ADO operations without the aid of the ADO Data control: –Establish a connection to a data source –Define a command –Execute the command –Commands may or may not return records. If they do, create a recordset. –Manipulate the records in the recordset as desired.

ADO Object Hierarchy A Connection object represents an open connection to a data source. Connection Command Recordset Errors

Connection Object Properties ConnectionString ConnectionTimeout CommandTimeout Mode Provider

Connection Object Methods Open Close BeginTrans CommitTrans RollbackTrans

Building the Connection Object Programmatically Create an instance of an ADO Connection object Set the necessary arguments for the ConnectionString property of the Connection object. Call the Open method of the Connection object.

ConnectionString Property The ConnectionString property is a string with which you specify a data source. It defines connection information in the form of argument = value pairs separated by semicolons (;). ADO supports the following arguments: –Provider –Data Source –User ID and Password –File Name –Remote Provider and Remote Server

Creating an Instance of the ADO Object You must create an instance of a particular ADO object before you can use it. Example: Dim conMagnet As New ADODB.Connection

Private Sub Form_Load() ' Declare the Connection object. Dim conMagnet As New ADODB.Connection ' Define the properties for the Connection object ' then open the connection. conMagnet.Mode = adModeShareDenyNone conMagnet.CursorLocation = adUseClient conMagnet.Provider = "Microsoft.Jet.OLEDB.4.0" conMagnet.ConnectionString = "Data Source=A:\Magnet.mdb” conMagnet.Open End Sub

The Command Object Properties –ActiveConnection –CommandType adCmdText, adCmdTable, adCmdStoredProcedure –CommandText –CommandTimeout Methods –Execute –Cancel

Private Sub Form_Load() ' Declare the Connection and Command objects. Dim conMagnet As New ADODB.Connection Dim cmdMagnet As New ADODB.Command ' Define the properties for the Connection object ' then open the connection. conMagnet.Mode = adModeShareDenyNone conMagnet.CursorLocation = adUseClient conMagnet.Provider = "Microsoft.Jet.OLEDB.4.0" conMagnet.ConnectionString = "Data Source=A:\Magnet.mdb" conMagnet.Open ' Define the propeties for the Command object. Set cmdMagnet.ActiveConnection = conMagnet cmdMagnet.CommandType = adCmdTable cmdMagnet.CommandText = "tblOrderMaster“ End Sub

' Module level variable to store a reference to the form's recordset. Private rstCurrent As New ADODB.Recordset Private Sub Form_Load() Dim conMagnet As New ADODB.Connection Dim cmdMagnet As New ADODB.Command conMagnet.Mode = adModeShareDenyNone conMagnet.CursorLocation = adUseClient conMagnet.Provider = "Microsoft.Jet.OLEDB.4.0" conMagnet.ConnectionString = "Data Source=A:\Magnet.mdb" conMagnet.Open Set cmdMagnet.ActiveConnection = conMagnet cmdMagnet.CommandType = adCmdTable cmdMagnet.CommandText = "tblOrderMaster“ rstCurrent.Open cmdMagnet End Sub